# Tagged Questions

On a map, a closed shape defined by a connected sequence of x,y coordinate pairs, where the first and last coordinate pair are the same and all other pairs are unique.

80 views

### How to re-ID polygons with sapply instead of for loop

I have a line of code that renames the id's of polygons in a SpatialPolygonsDataFrame by directly manipulating the ID slot of the polygon. I'm a bit slow when it comes to sapply, having used for loops ...
332 views

### How to extract common outline of multiple polygons with code?

I'm not really asking for a chunk of code to do this, but more of an algorithm I can work with myself. For example, this is the state of Maine, obviously, and I have the points of each county ...
828 views

### How to calculate the percentage of distribution in each polygon?

I have binary map for disease suitable area and I want to calculate the percentage using pixel count in each polygon how can I do that? I use zonal histogram and do have frequency for each polygon is ...
154 views

### Using ST_Affine() and trans_param() functions on vector layer

After reading this post How to georeference a vector layer with control points? I decided to give it a try to move/rotation/scale a polygon using Postgis. I have two polygons, polygon_from and ...
313 views

### Separate a polygon in different polygons depending of the distance to another polygon

I have a reference polygon "R", and others polygons (in grey). I want to separate each grey polygon in multiple polygons, depending on the distance to R with different Buffers : - The red line is R ...
4k views

### How do I set the fillcolor of polygons in Leaflet.js dynamically?

I'm using the interactive chloropath example for leaflet.js I figured out how to make each of my polygons add a running tally of values to the bottom of the page after each polygon is clicked. Upon ...
1k views

### PostGIS: Calculate the length of just the portion of linestring that intersect with a polygon

I want to calculate the portion of the linestring that lies within the limits of a polygon. Better with an image What is the length of the portion of linestring within Province A? and within ...
80 views

### ArcGIS10 Highest point via polygon features

I am using ArcGIS 10.0 with 3D Analyst, Spatial Analyst and Military Analyst. I feel like I am halfway to solving a problem but do not seem able to completely solve it. I have a polygon shapefile ...
311 views

### Merge polygon without attribute (in field) with nearest polygon with attribute

In the image you can see districts in BLUE with attributes (name of district) and small pieces in RED. The red polygons belong to the blue and I want to merge them. The RED are only towards the ...
2k views

### How to export polygon coordinates?

How can I export each polygon-vertice's coordinate (every point coordinate of every polygon) of a polygon Geodatabase-feature class to an ascii text file (csv or txt)? I don't want to convert it to a ...
173 views

### How to automate creating box (rectangular) polygons in ArcGIS for Desktop?

Can anyone suggest a way to automate creating rectangle shaped polygons in ArcMap? If I had many 30m x 60m rectangles to digitize and I just want to click a starting corner coordinate on screen, ...
6k views

### How to calculate centroid of a polygon defined by a list of longitude/latitude points? [duplicate]

I've imported some polygons (ways) from OpenStreetMap and now want to calculate the centroids of them. For this purpose I wrote following code: final List<Point2D.Double> points = ...
91 views

### Raster Data to Polygon [closed]

I need to "translate" raster information to a set of polygons. The raster to polygon tool will not work. I created a fishnet with the same resolution of the raster and converted it to polygons. I now ...
615 views

### Search for geojson polygon in mongodb implementing a custom vector tileserver

I am building a vector tileserver in node.js using mongo 2.4.7 as database. My database contains geojson data from multiple sources and they are in many layers. It is important to render the layers ...
5k views

### Does MySQL has function which will return the points inside polygon?

I have MySQL database with polygons, and also the database with points (column longitude and column latitude), is it possible to return all points inside one polygon? Thanks!
273 views

### Does spherical equilateral triangle T contain point P?

I am working on a Python script to: compute the vertex coordinates of a geodesic sphere/icosahedron, project the triangles onto a sphere, then find which spherical triangle contains an arbitrary ...
5k views

### Intersect (analysis) of polygons generating empty output

I have previously asked a question on determining the area of polygons with another polygon boundary. Determining the area of each polygon within a polygon boundary? I came to the conculsion that ...
391 views

### Locating the centroid (center of mass) of spherical polygons

I'm trying to work out how best to locate the centroid of an arbitrary shape draped over a unit sphere, with the input being ordered (clockwise or anti-cw) vertices for the shape boundary. The density ...
1k views

### QGIS Polygon precision

Is there a way to edit the precision of polygon points in QGIS so that each coordinate has the same number of decimal places? For example, the coordinate 23.18273917, -84.29172638491 would be ...
1k views

### How to narrow the result from Nominatim with only cities and countries, no additional areas with the same name?

I'm trying to get WKT or GeoJson polygons of cities and countries from Nominatim (for example, Paris and France). I send a GET request but it returns me several results named "Paris" or "France". How ...
2k views

### How to get WKT or GEOJson by country or city name with Overpass API?

I'm trying to understand Overpass API, I'm experimenting with it, but cannot get what I expect. Overpass API doesn't return me neither polygon shapes, nor WKT, nor GEOJson, nor even a highlight of the ...
2k views

### How to get a list of OSM relations (id numbers) of cities and countries only?

I want to get OSM polygon shapes (GEOJson or WKT) of countries and cities only. I know that it is called a "relation" in OSM and each relation has its own id (New York is 175905, for example). How may ...
751 views

### Determining the area of each polygon within a polygon boundary?

I have a series of maps representing a 1000m diameter around a point. These maps contain 40 different types of polygons that represent a land use (ex. Corn crop, Pasture). I want to select all ...
267 views

### Line features into polygon features

Can any one tell me how to convert line features into polygon features in ArcGIS. I am using ArcGIS 10. I searched the arc toolbox for any tools for this conversion, but I couldn't find any. Please ...
303 views

### Heads up digitizing - Polygons overlay differently with two different Satellite images

I have been digitizing building footprints from satellite image using ArcGIS 10.1 . Field data collections is done with the use of four corner point GPS way point. Due to multipath errors, we are ...
472 views

### Calculating minimum/maximum width for overlay of two polygon strips in ArcGIS or some Opensource GIS

Is there some solution for calculating minimum and maximum width for overlay of two polygon strips? When I clip these strips the result is another strip with variable width about 1 km and 20 km long. ...
32 views

### Selecting Polygon Features in QGIS Lisboa

I want to select and save as a separate shape file, a smaller section (polygon) from a whole island country which includes both land and shallow habitat coastal features (like coral reefs) and when I ...
81 views

### Generating vineyard's rows in a polygon

Does anyone know if it's possible to generate line (the distance between each one is 2 meters) in a polygon?
965 views

### Simple way to detect/select border polygons of a shapefile

I am looking for a simple way to detect/select border polygons of a shapefile. Border polygons are here polygons that are not completely surrounded by other polygons i.e. polygons located at the ...
399 views

### Postgis identify points on the polygon border

I have points geom in gid,pt_geom and polygon geom in gid,pl_geom. Some of the points are inside polygon and some are outside polygon, others are on the polygon boundary. Is there any way to ...
31 views

### calculating mean and standard deviation for raster values using whole pixels within a polygon [duplicate]

i have a raster image and a corresponding shape file. i would like to calculate the statistics of the values within polygons which have a common attribute but only using pixels which are fully ...
571 views

### Drawing polygons with Google Maps using local shape data

I am trying to draw a census tract on a Google map. It looks like Google Maps lets you draw polygons using longitude and latitude coordinates. However, the data that I have is not ...
78 views

### When digitizing, polygons are inverted

I need to use QGIS to digitize my images. My images are scanning electron microscope (SEM) images of rocks. I am interested in analyzing the pore space in the images. Here is the steps I follow: I ...
773 views

### Lossless Polygon Simplification?

Is there a standard/recommended algorithm for simplifying a polygon without shrinking any of its original boundaries? Right now I'm using TopologyPreservingSimplifer within JTS and running into ...
905 views

### “Identity” overlay in QGIS?

I have two polygon layers I'd like to overlay using QGIS or another open source tool. What I want as output is a polygon layer with the extent of one polygon, but with each polygon in that layer ...
731 views

### How to get polygon coordinates for Google Map from .poly files (preferably in nodejs)?

I have .poly files with polygons of countries. I want to use those polygons to make Google Map polygon layers. How may I read lng and lat points of polygons from those poly files? They look like ...
1k views

### ARCGIS 10- Cutting down a tiff file layer to a smaller polygon?

I have a dynamic land map featuring open forest, closed forest ect of an area which is a tiff layer file. I want to be able to cut the layer file to my area of interest, the polygon I created? I also ...
62 views

### Delete polygon underlap?

I am editing a layer in QGIS with severe polygon overlaps. Is there a way to delete the underlapping portions (i.e. the invisible parts) using QGIS? If I import the layer into GRASS using the ...
161 views

### Postgis 2.0 geographic polygon has max longitudinal range

My problem is that I have a load of geographic point data (srid 4326) in a table. A user may do a bounding box search - essentially create a polygon as follows: l_poly geography(Polygon,4326):= ...
446 views

### intersection between two multipolygons yielding anomalous GeometryCollection object full of LineString's & Polygon's (trying to get intersect area)

Normally when I call the #intersection method on a multipolygon to find the intersection shape on another multipolygon I get a multipolygon returned back to me. Either that or something else I can ...
670 views

### JTS Polygon simplification without holes

I have a set of polygons without holes. I wish to merge any intersecting polygons. I don't want to have any holes in my simplified polygons. Is there a recommended way to achieve this using JTS? The ...
579 views

### Create MultiPolygon from QgsGeometry.fromMultiPolygon

I have a list of polygons' points like [[x1,y1],[x2,y2],[x3,y3],[x4,y4]] [[x5,y5],[x6,y6],[x7,y7].[x8,y8]] now I want to create multipolygon from it by using feature = QgsFeature() ...
3k views

### How to remove small “salt & pepper” polygons from a layer?

I have a map made up of multiple polygons, with a few hundred thousand points very small polygons on within it. I need the larger polygons, but not the points small polygons. How do I select and ...
20k views

### How to Merge/Dissolve Polygons By Common Attribute Field in QGIS?

I have joined corresponding Local Enterprise Partnerships table data into a polygon shape file containing UK Local Authorities. How do I Dissolve or Merge the the Local Authorities polygons by ...
61 views

### Dissolving overlapping polygons - issue in QGIS [duplicate]

I have the OS Code-Point map which I want to dissolve into the regions that my company use. I have used the dissolve function in QGIS, but it is having a problem where a vertical street overlaps with ...
145 views

### How to find out to which polygon each points belongs to?

I have searched for an answer to this, but couldn't find anything useful. I have got a shapefile consisting of a number of polygons, and another shapefile with a number of points. I want to add a ...
301 views

### QGIS point sampling tool really slow for polygons?

I have a large field of randomly distributed points (100,000 of them to be precise), and I'd like to get values for a variety of raster and polygon coverages for each point. I've been using the QGIS ...
128 views

### What is the best format to encode polygons such as lakes?

I am looking for a standard format to encode polygons, such as lakes, in one file that is easy to create and common so that others can use it in different GIS systems. Every file will contain data on ...